Catheter having a variable length shaft segment and method of use

ABSTRACT

The invention relates to a catheter device and a method of use to enable catheter exchange over a conventional length guidewire without the use of a guidewire extension or exchange wire. The catheter device includes an elongated inflation shaft having a longitudinal inflation lumen, an extension shaft having a longitudinal extension lumen coupled in fluid communication with the inflation lumen, a balloon member disposed at the distal end of the extension shaft and in fluid communication with the inflation lumen, a guidewire shaft having a longitudinal guidewire lumen which extends from the distal end of the balloon member, through the balloon member and extension shaft, to the proximal end of the extension shaft, and a variable length shaft coupled to the proximal end of the extension shaft. The variable length shaft comprises an elastomeric material which may be stretched from a relaxed state of about 10 centimeters to a fully extended state of about 140 centimeters.

FIELD OF THE INVENTION

The present invention relates to catheter systems employed inintravascular procedures. More particularly, the present inventionrelates to a catheter device and exchange system for facilitating theexchange of catheters and/or guidewires, and for the transport of suchcatheters and/or guidewires to a selected site within the patient'svasculature without the need for guidewire extensions or exchange wires.

BACKGROUND OF THE INVENTION

Catheters are widely used by the medical profession for a variety ofpurposes and procedures. For example, catheters are commonly used in thetreatment of atherosclerotic lesions or stenoses formed on the interiorwalls of the arteries. One procedure developed for the treatment of suchlesions or stenoses is coronary angioplasty. The most commonly practicedangioplasty procedure is known as percutaneous transluminal coronaryangioplasty, or PTCA. According to this procedure, a dilatation catheterhaving a balloon located at its distal end is guided through thepatient's vasculature such that the balloon is positioned within thestenosis. When the catheter is advanced through the patient'svasculature to the treatment site, the balloon is in a deflatedcondition such that the catheter has a minimum cross-section. Theballoon is then inflated one or more times to dilate the stenosis andopen the restricted area of the artery. Finally, the balloon is deflatedand the catheter is removed from the patient's vasculature.

Typically, the dilatation catheter is maneuvered through the patient'svasculature with the use of a flexible guidewire having a diameter ofapproximately 0.010 to 0.018 inches and a length of about 180centimeters. The distal end of the guidewire is extremely flexible sothat it may be routed through the convoluted arterial pathway to thesite of the stenosis. After the distal portion of the guidewire ispositioned across the stenosis, a dilatation catheter having a lumenadapted to receive the guidewire is advanced. over the guidewire untilthe balloon is positioned within the stenosis. Alternatively, theguidewire and catheter may be advanced together within the patient'svasculature to the treatment site with the distal end of the guidewireprotruding from the distal end of the catheter.

The prior art includes three types of catheters for use with aguidewire: "over-the-wire" catheters, "rapid exchange" catheters and"fixed-wire" catheters.

A conventional over-the-wire catheter comprises a guidewire lumen whichextends throughout the length of the catheter. In use, the guidewire isdisposed entirely within the catheter guidewire lumen except for itsproximal and distal ends which protrude from the proximal and distalends of the catheter, respectively. A typical over-the-wire balloondilatation catheter is disclosed in Simpson et al. U.S. Pat. No.4,323,071.

Such over-the-wire catheters have many advantages attributable to thefull-length guidewire lumen. For example, these type catheters have goodstiffness and pushability for advancing the catheter through theconvoluted vasculature to the treatment site. Further, the guidewirelumen provides a continuous conduit between the proximal and distal endsof the catheter for transporting radiocontrast dye to the treatment siteor for enabling pressure measurements. In addition, the full-lengthguidewire lumen allows for the exchange of guidewires within anindwelling catheter, should that be desired.

Despite these advantages, there are many undesirable complicationsassociated with the use of over-the-wire catheters. For example, duringa catheterization procedure, it may be necessary to thread a catheter onor off an indwelling catheter, or exchange an indwelling catheter foranother catheter over an indwelling guidewire. When advancing orwithdrawing a catheter over an indwelling guidewire, the physician mustgrip the proximal portion of the guidewire extending outside the patientto maintain the position of the distal portion of the guidewire acrossthe treatment site. However, the length of a conventional over-the-wirecatheter, typically on the order of 135 centimeters, is greater than thelength of the proximal portion of a standard guidewire which protrudesout of the patient. Accordingly, it is necessary to extend the guidewirea sufficient distance outside the patient so that the physician maymaintain his or her grip on the proximal portion of the guidewire whilethreading an over-the-wire catheter on or off an indwelling guidewire.The additional length of guidewire needed may be provided by a guidewireextension which is temporarily "linked" or attached to the proximal endof the guidewire. Once the catheter has been threaded onto the guidewireextension and advanced over the guidewire through the patient'svasculature, the guidewire extension may be detached from the guidewire.

Alternatively, an exchange wire, typically on the order of 300centimeters, may be guided through the patient's vasculature such thatits distal portion is positioned across the stenosis. The proximalportion of the exchange wire protruding out of the patient is ofsufficient length such that the physician may maintain his or her gripon the proximal portion of the guidewire while advancing the catheterover the guidewire. After the balloon located at the distal end of thecatheter is positioned within the stenosis, the exchange wire may beremoved from the guidewire lumen and replaced with a shorter, easier tohandle guidewire.

A number of alternative catheter designs have been developed in anattempt to address these issues. One such design is the fixed-wirecatheter, which comprises a catheter having an internally fixedguidewire or stiffening element. Catheters of this design are readilymaneuverable and relatively easy to position within the patient'svasculature without the use of a separate guidewire. However, becausethese catheters do not use a separate guidewire, the administeringphysician is unable to maintain guidewire access to the treatment sitewhile removing the catheter. Thus, if it were necessary to perform acatheter exchange, the physician must remove the indwelling catheter andrenegotiate the arterial pathway to the treatment site with thereplacement catheter.

Another alternate design is the "rapid exchange" type catheter andguidewire system. Generally, a rapid exchange catheter includes aguidewire lumen which extends along only a short shaft section near thedistal end of the catheter. Accordingly, when the catheter is advancedover the guidewire, the guidewire is located outside the catheter exceptfor the short segment which passes through the guidewire lumen at thedistal end of the catheter. In use, a conventional length guidewire isrouted through the patient's vasculature such that its distal end ispositioned across the treatment site. The distal end of the catheter isthen threaded onto the proximal end of the guidewire. Since theguidewire lumen is relatively short, a rapid exchange catheter may befully threaded onto the guidewire without linking an extension wire orusing a long exchange wire. Similarly, when it is desired to perform acatheter exchange procedure, the catheter may be withdrawn over anindwelling guidewire without the use of a guidewire extension or anexchange wire.

Although such a rapid exchange catheter system may eliminate the needfor an extension wire or a long exchange wire, it presents significantdisadvantages. For example, because these catheters have a truncatedguidewire lumen, they do not provide the same stiffness and pushabilityas an over-the-wire catheter. Further, it has been found that as thesecatheters are advanced or withdrawn over a guidewire, the exposedportion of the guidewire may buckle or bow relative to the catheter andpossibly inflict damage to the inner walls of the patient's vasculature.Furthermore, there exists a significant risk of quidewire entanglementin procedures involving multiple guidewires. In addition, unlikeover-the-wire catheters, it is not possible to exchange guidewires in anindwelling rapid exchange catheter.

Therefore, there exists a need for an improved catheter device andmethod of use which incorporates the benefits of both the over-the-wirecatheters and the rapid exchange catheters, but without their attendantdrawbacks.

OBJECTS AND SUMMARY OF THE INVENTION

In accordance with the present invention, a catheter device having avariable length guidewire lumen is provided for insertion into a patientover a conventional length guidewire. The catheter includes an elongatedinflation shaft having a longitudinal inflation lumen, an extensionshaft disposed distal to the inflation shaft, a balloon member disposedat the distal end of the extension shaft, a guidewire shaft having alongitudinal guidewire lumen which extends from the distal end of theballoon member, through the balloon member and the extension shaft, tothe proximal end of the extension shaft, and a variable length shaftcoupled adjacent the proximal end of the extension shaft. The extensionshaft includes an extension lumen having a proximal end in fluidcommunication with the distal end of the inflation lumen and a distalend in fluid communication with the interior of the balloon. Thevariable length shaft comprises a stretchable tube formed of anelastomeric material and having a length selectively variable from about10 centimeters to about 140 centimeters.

When the catheter is threaded over an indwelling guidewire or when thecatheter is being exchanged with another catheter, the variable lengthshaft is in a relaxed state having a length of about 10 centimeters. Thedistance from the proximal end of the variable length shaft to thedistal end of the guidewire shaft is sufficiently short that thecatheter may be threaded onto or removed from the indwelling guidewirewithout the use of an extension wire. Further, as the catheter isadvanced over the guidewire through the patient's vasculature, thevariable length shaft. stretches from its shortest length of about 10centimeters to its longest length of about 140 centimeters, therebycapturing the entire length of the guidewire extending between theproximal end of the catheter and the proximal end of the guidewirelumen.

It is, therefore, a principal object of the present invention to providean improved catheter and guidewire system which enables loading andunloading of the catheter over an indwelling guidewire without the useof an extension wire, and the exchange of the guidewire withoutcompromising the position of the indwelling catheter.

It is a further object of the present invention to provide an improvedcatheter and guidewire system, wherein the catheter includes a variablelength shaft which provides an essentially constant cross-sectionaldiameter when it is at any position between a fully extended or fullyretracted state.

It is a further object of the present invention to provide an improvedcatheter and guidewire system, wherein the catheter includes a variablelength shaft which provides a smooth interior surface when it is at anyposition between a fully extended or fully retracted state.

Objects and advantages of the invention are set forth in part above andin part below. In addition, these and other objects and advantages ofthe invention will become apparent herefrom, or may be appreciated bypractice with the invention, the same being realized and attained bymeans of instrumentalities, combinations and methods pointed out in theappended claims. Accordingly, the present invention resides in the novelparts, constructions, arrangements, improvements, methods and stepsherein shown and described.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described, by way of example, withreference to the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view of the variable length shaft catheterof the present invention with the variable length shaft in its relaxedstate;

FIG. 2 is a cross-sectional view of the variable length shaft cathetertube of the present invention with the variable length shaft in anelongated state;

FIG. 3 is a cross-sectional view of the variable length shaft cathetershown in FIG. 2 along line 3--3;

FIG. 4 is a cross-sectional view of the variable length shaft cathetershown in FIG. 2 along line 4--4; and

FIG. 5 is a cross-sectional view of the variable length shaft cathetershown in FIG. 2 along line 5--5;

FIG. 6 is a cross-sectional view of the variable length shaft cathetershown in FIG. 2 along line 6--6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

It should be noted that while the following description will bespecifically in the context of coronary angioplasty dilatationcatheters, the invention is not so limited and is applicable to othercatheter assemblies and procedures. For example, it will be understoodthat the present invention also applies to drug delivery and/or stentdelivery catheters.

Referring generally to the embodiments of the invention shown in theaccompanying drawings, wherein like reference numbers refer to likeparts throughout the various views, the basic principles of the broadestaspects of the invention can be appreciated from FIGS. 1-6.

As shown in FIG. 1, the variable length shaft catheter of the presentinvention, which is designated generally as 10, includes an elongatedinflation shaft 20, an extension shaft 30, a balloon member 38, aguidewire shaft 40, and a variable length shaft 50.

The inflation shaft 20 includes a proximal end 22, a distal end 24, andan inflation lumen 26 extending longitudinally throughout its length.Preferably, inflation shaft 20 is formed from stainless steel hypotubeto provide the catheter with sufficient stiffness and pushability. Theproximal end 22 of inflation shaft 20 is coupled to a fitting 28, whichis designed to enable fluid communication between inflation lumen 26 anda source of pressurized inflation fluid (not shown). Preferably, fitting28 is in the form of a female luer fitting.

The extension shaft 30 includes a proximal end 32, a distal end 34, andan extension lumen 36 extending longitudinally throughout its length. Asillustrated in FIGS. 1 and 2, the proximal end 32 of extension shaft 30is disposed adjacent the distal end 24 of inflation shaft 20. Further,extension lumen 36 is coupled in fluid communication with inflationlumen 26, such that inflation lumen 26 and extension lumen 36 form acontinuous conduit enabling fluid communication from the proximal end ofinflation shaft 20 to the distal end of extension shaft 30. Extensionshaft 30 may be formed from a flexible polymer material such aspolyvinyl chloride, polyethylene terephthalate or, preferably, highdensity polyethylene. In a preferred embodiment, the distal end ofinflation shaft 20 and the proximal end of extension shaft 30 arecoupled via an extension tube 60. According to this configuration,extension tube 60 provides a fluid communication pathway betweeninflation lumen 26 and extension lumen 36. Preferably, extension tube 60is formed from stainless steel hypotube.

The balloon member 38 is disposed adjacent the distal end of extensionshaft 30. Balloon member 38 may be formed from polyvinyl chloride,polyethylene, polyurethane or preferably, polyethylene terephthalate.The interior of balloon 38 is in fluid communication with the distal endof extension lumen 36.

The guidewire shaft 40 has a proximal end 42, a distal end 44, and aguidewire lumen 46 extending longitudinally throughout its length.Guidewire shaft 40 may be formed from a flexible polymer material, suchas polyvinyl chloride, polyethylene terephthalate or, preferably, highdensity polyethylene. As illustrated in FIGS. 1 and 2, guidewire shaft40 is longitudinally disposed within extension shaft 30 and extendsthrough balloon member 38, whereby the distal end 44 of guidewire shaft40 extends beyond the distal end of balloon member 38. The distal end ofballoon member 38 is coupled to guidewire shaft 40.

Guidewire lumen 46 is dimensioned to slidably receive a standardcoronary angioplasty guidewire (not shown). As shown in FIG. 3, at theproximal portion of extension shaft 30, guidewire shaft 40 and extensiontube 60 are disposed in a parallel arrangement, thereby providing aside-by-side dual lumen cross section. As shown in FIG. 4, at the distalend of extension shaft 30, guidewire shaft 40 extends longitudinallythrough extension lumen 36, thereby providing a coaxial dual lumen crosssection. To this end, the outer diameter of guidewire shaft 40 isdimensioned such that extension lumen 36 forms an annular flow passagewith sufficient inflation flow capacity to permit acceptable ballooninflation and deflation rates. Alternatively, it will be understood thatguidewire shaft 40 may be disposed in parallel arrangement withextension tube 60 and extension lumen 36 to provide a side-by-side duallumen cross-section throughout the length of extension shaft 30.

The variable length shaft 50 comprises a tube having a proximal end 52and a distal end 54. Variably length shaft 50 is formed of a highelongation, resilient, elastomeric material, which may be stretched froma relaxed state having a length of about 10 centimeters to a fullyelongated state having a length of about 140 centimeters. Preferably,variable length shaft 50 is formed of an unsaturated styrene/rubbermaterial, e.g., Kraton™, which is sold by Shell Chemical Co. As shown inFIGS. 1 and 2, the distal end of variable length shaft 50 is sealinglycoupled to the proximal end of extension shaft 30. In a preferredembodiment, variable length shaft 50 is coupled about the outsidesurface of extension shaft 30 such that when it is in an extended stateit encompasses inflation shaft 20 (see FIG. 5). Alternatively, variablelength shaft 50 may be coupled to the proximal end of extension shaft 30such that it extends longitudinally in a side-by-side arrangement withinflation tube 20. Further, the catheter of the present invention may beadapted to have a plurality of variable extension shafts for use inprocedures requiring multiple guidewires.

As illustrated in the preferred embodiment depicted in FIGS. 1 and 2,the proximal end of variable length shaft 50 is coupled to ananti-backbleed hub 56. Anti-backbleed hub 56 functions to prevent thebackflow of fluids between the guiding catheter and catheter 10.Preferably, anti-backbleed hub 56 comprises a tubular member having aflanged lip at its proximal end for abutment with the Tuohy-Borstadapter. As shown in FIG. 6, anti-backbleed hub 56 includes a centralport through which inflation shaft 20 and a guidewire (not shown) canpass.

In addition, anti-backbleed hub 56 may be designed to act as a stop oranchor which prevents the longitudinal movement of inflation shaft 20within variable length shaft 50. To this end, anti-backbleed hub 56 isformed of a compressible material, such that when the Tuohy-Borstadapter is closed and locked down on the outer surface of anti-backbleedhub 56, anti-backbleed hub 56 is radially compressed such that itsinside surface grips and locks down on inflation shaft 20.

Operation and use of the variable length shaft catheter of the presentinvention is described as follows. A guiding catheter (not shown in theFIGS.) is inserted into the patient's vasculature in a conventionalmanner. A Tuohy-Borst adapter (not shown in the FIGS.) is then disposedat the proximal end of the guiding catheter. Next, the Tuohy-Borstadapter is opened to receive a standard length guidewire. The guidewireis routed through the patient's vasculature until the guidewire distalportion is positioned across the treatment site. The Tuohy-Borst adapteris then closed such that it locks down on the guidewire. With catheter10 in a relaxed state as shown in FIG. 1, catheter 10 is threaded overthe guidewire by inserting the proximal end of the guidewire into thedistal end of guidewire lumen 46. The catheter is then advanced over theguidewire until the anti-backbleed hub 56 engages the Tuohy-Borstadapter. Because catheter 10 is in a relaxed state and has a minimumover-the-wire length, the proximal end of the guidewire protrudes outthe proximal end of guidewire lumen 46. The Tuohy-Borst adapter is thenclosed until it locks down and is securely coupled to the anti-backbleedhub 56.

Catheter 10 is advanced over the indwelling guidewire by holding theproximal end of the guidewire and pushing the proximal end of inflationshaft 20 in a direction toward the Tuohy-Borst adapter until balloonmember 38 is positioned across the treatment site. Since the proximalend and the distal end of variable length shaft 50 are coupled toextension shaft 30 and anti-backbleed hub 52, respectively, advancementof catheter 10 through the patient's vasculature will cause variablelength shaft 50 to stretch, and thereby encase the portions of theguidewire and inflation shaft 20 extending between the distal end ofextension shaft 30 and the Tuohy-Borst adapter.

Accordingly, as catheter 10 is advanced over the guidewire, the variablelength shaft 50 and guidewire lumen 46 effectively form a full-lengthguidewire lumen. As such, medications, saline or radiocontrast dye, canbe delivered to the treatment site by way of injection intoantibackbleed hub 52 and through the fluid passageway created byvariable length shaft 50 and guidewire lumen 36.

Once balloon member 38 has been positioned across the treatment site,pressurized inflation fluid may be injected through fitting 28 by theuse of a hand syringe or any other pressurizing device known in the art(not shown in the FIGS.). The inflation fluid passes through fitting 28,inflation lumen 26, extension tube 60 and extension lumen 36, beforeentering balloon member 38. The inflation of balloon member 38 can beobserved if radiographic contrast liquid is used as the inflation fluid.As balloon member 38 is inflated with pressurized inflation fluid, itpresses against the treatment site and dilates the stenosis.

During a catheterization procedure, it may be necessary to exchange theindwelling catheter with another catheter having a different feature.For example, it may be desired to follow a balloon dilatation procedurewith a drug delivery or stent delivery procedure. Likewise, in the eventthe balloon on the indwelling catheter is too small to sufficientlydilate the stenosis, the administering physician may elect to exchangethe indwelling catheter with another catheter having a larger balloon.As provided in the present invention, variable length shaft 50 ofcatheter 10 provides a means for catheter exchange without the use of anextension wire or an exchange wire.

It is understood that during catheter exchange procedures, it isdesirable to maintain the position of the distal end of the guidewireacross the treatment site. To effect an exchange of catheter 10, theadministering physician holds the proximal end of the guidewire in afixed position. In addition, the physician grips and pulls the proximalend of inflation shaft 20 such that the catheter is withdrawn from thepatient over the guidewire. As the catheter is withdrawn from thepatient, variable length shaft 50 retracts and is reduced in lengthuntil it reaches its relaxed length. The Tuohy-Borst adapter is thenopened and decoupled from the anti-backbleed hub 56. While maintainingthe position of the distal end of the guidewire across the treatmentsite, the administering physician removes the catheter 10 from theproximal end of the guidewire. It will be understood that the effectiveover-the-wire length of the catheter when variable length shaft 50 is inits relaxed state is sufficiently short to enable removal of thecatheter without the use of an extension wire. After the originalcatheter is removed, a second catheter in the form of the presentinvention may be threaded over the guidewire as described above.

While only a few embodiments have been illustrated and described inconnection with the present invention, various modifications and changesin both the apparatus and method will become apparent to those skilledin the art. All such modifications or changes falling within the scopeof the claims are intended to be included therein.

We claim:
 1. A catheter device having a variable length guidewire lumenadapted for use with a conventional length guidewire, comprising:(a) anelongated inflation shaft having a proximal end, a distal end and aninflation lumen extending longitudinally therethrough; (b) an extensionshaft having a proximal end, a distal end and an extension lumenextending longitudinally therethrough, the extension shaft proximal endbeing disposed adjacent the distal end of the inflation shaft such thatthe inflation lumen and the extension lumen are in fluid communicationand form a continuous passageway therethrough; (c) a guidewire shafthaving a proximal end, a distal end and a guidewire lumen extendingtherethrough, the guidewire shaft disposed longitudinally throughout thelength of the extension shaft, the distal end of the guidewire shaftextending beyond the distal end of the extension shaft, and theguidewire lumen dimensioned to slidably receive the guidewire; (d) aballoon member having a distal end and a proximal end, the proximal endof the balloon member being coupled to the distal end of the extensionshaft, the distal end of the balloon member being coupled to theguidewire shaft adjacent the distal end of the guidewire shaft, theballoon member defining an interior cavity in fluid communication withthe extension lumen; and (e) a variable length shaft formed of anelastomeric material which may be stretched from a relaxed state ofabout 10 centimeters to a fully elongated state of about 140centimeters, the variable length shaft having a proximal end, a distalend and an interior surface, wherein the distal end is coupled to theextension shaft and the interior surface is substantially uniform at anylength of the shaft from the relaxed state to the fully elongated state.2. The catheter device of claim 1, which further comprises ananti-backbleed hub coupled to the proximal end of the variable lengthshaft, the anti-backbleed hub having a central port dimensioned topermit the inflation shaft and guidewire to pass therethrough.
 3. Thecatheter device of claim 1, which further comprises an extension tubewhich provides a fluid communication passageway between the inflationlumen and the extension lumen.
 4. The catheter device of claim 1,wherein the distal end of the variable length shaft is coupled about anoutside surface of the extension shaft, the variable length shaftextends longitudinally in coaxial relation with the inflation shaft suchthat as the variable length shaft is extended from the relaxed state toan elongated state it encases the inflation shaft.
 5. The catheterdevice of claim 1, wherein the inflation shaft is formed from hypotube.6. The catheter device of claim 1, which further comprises a fittingcoupled to the proximal end of the inflation shaft to enable fluidcommunication between the inflation lumen and a source of pressurizedfluid.
 7. A method for loading and unloading a balloon catheter devicehaving a variable length shaft segment over a conventional lengthguidewire without the use of an exchange wire or a guidewire extension,the method comprising the steps of:(a) inserting a guiding catheter in apatient's vasculature; (b) disposing an adapter at the proximal end ofthe guiding catheter, such that the adapter is positioned outside thepatient's body; (c) opening the adapter and inserting the conventionallength guidewire having a distal end and a proximal end into the guidingcatheter and advancing the distal end of the guidewire to a treatmentsite within the patient's vasculature; (d) loading the balloon catheterover the proximal end of the guidewire and advancing the ballooncatheter through the adapter into the guiding catheter; (e) coupling theballoon catheter to the adapter; (f) maintaining the distal end of theguidewire in position across the treatment site by gripping theguidewire at a position proximate to the adapter; (g) advancing theballoon catheter over the guidewire such that a balloon member of theballoon catheter is across the treatment site by pushing an inflationshaft of the balloon catheter toward the adapter and thereby stretchingthe variable length shaft segment from a relaxed state to a fullyelongated state; (h) unloading the balloon catheter by gripping theinflation shaft proximate the adapter and withdrawing the inflationshaft through the adapter until the variable length shaft segment is inthe relaxed state; (i) decoupling the balloon catheter and the adapter;(j) gripping the proximal end of the guidewire with one hand and pullingthe inflation shaft until the balloon catheter is withdrawn from thepatient; and (k) gripping the guidewire at a position distal the ballooncatheter and pulling the balloon catheter off the proximal end of theguidewire.